Gas generation and management system

ABSTRACT

A system for generating gas includes a gas source which includes a gas generator and a gas compressor. The system also includes a gas management apparatus in a flow path between the gas source and gas sink. The gas management apparatus includes a primary pressure vessel that stores gas when a gas source flow rate exceeds a gas sink flow rate, and that releases stored gas when the gas source flow rate is less than the gas sink flow rate. The gas management apparatus also includes a primary variable state material that absorbs the gas when in an absorptive state, and releases the gas in a releasing state.

FIELD OF THE INVENTION

This invention relates to a hydrogen generation and management system.More particularly, this invention relates to hydrogen generation andmanagement system for powering a vehicle.

BACKGROUND OF THE INVENTION

Hydrogen as a source of fuel for combustion, particularly for poweringvehicles, has a great deal of generated interest, particularly in lightof the concerns over fossil fuel supplies. Prior systems for generatinghydrogen for use as a fuel supply for a vehicle have struggled toovercome several obstacles. For example, those systems that simply storehydrogen in hydrogen storage vessels must store the hydrogen at veryhigh pressures, up to 10,000 psi, in order to sustain operation for anylength of time. Such highly pressurized vessels may be under tremendousphysical stress, which may lead to leakage of the hydrogen gas. In asmuch as hydrogen is a very flammable liquid, such leakage presents anunacceptable explosion hazard. Further, to fully charge a large vesselto 10,000 psi would require expensive, professional equipment. Suchequipment is not readily available commercially, and is unlikely to bemade available to the average consumer. This greatly limits vesselrefilling options, which, in turn, greatly limits a consumer's abilityto utilize such a system. Other systems have endeavored to createhydrogen on-board. For example, fuel cell technology has been used.However, fuel cells are limiting because they are heavy, requireadditional complicated equipment, and are not yet economical.Consequently, there exists a need for a hydrogen generation system thatis safe, economical, and independent from commercial hydrogen fillingstations.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides an innovative gas generation andmanagement system that can generate gas and supply generated gas at avariety of gas demand rates while maintaining relatively low gaspressures within the system. Further, upon a system shut-down, the gasmanagement system will remove the substantial majority of the gas in thesystem, rendering the system safe. The gas generation and managementsystem may be connected to any device or system that requires gas,including, but not limited to a vehicle engine. The gas generation andmanagement system includes a gas generator, and a unique capacitancesystem that accumulates and dissipates the gas as required.Consequently, the gas generation and management system can accommodatesystems that demand steady flows of hydrogen, and advantageously, thegas generation and management system can supply gas to systems thatdemand gas at unsteady flow rates. Particularly advantageously, it cansupply gas for systems where the maximum gas demanded temporarilyexceeds the gas generation system's maximum gas generation rate, due tothe gas management system's gas capacitance. For example, the system canbe integrated into a vehicle, such that the gas generation andmanagement system can supply all the gas demanded, and can supply thegas at the rates demanded by the system, regardless of how that demandrate may change. Furthermore, the system may alternatively be used tosupplement another system present in a vehicle, such that the inventivesystem increases fuel mileage of the vehicle even though it is not thesole source of fuel for the vehicle. The embodiment described below isdirected toward a hydrogen gas generation and management system. Whilethe hydrogen generating portion of this system is limited to generatinghydrogen, as opposed to other gasses, it will become clear that any typeof gas can be managed by the gas management portion of the system, andthus the gas management portion of this system could be incorporatedinto systems that require management of gasses other than hydrogen. Allsuch embodiments are intended to be with the scope of this invention.

Accordingly, disclosed is a system for generating gas for a gas sink,wherein the gas sink consumes gas over a range of gas sink flow rates.The system contains a gas source with a gas generator and a gascompressor. The gas source generates the gas at a gas source flow ratethat varies from zero to a maximum gas source flow rate, and the maximumgas sink flow rate is greater than a maximum gas source flow rate. Thesystem further contains a gas management apparatus in a flow pathbetween the gas source and gas sink. The gas management apparatusincludes a primary pressure vessel. The primary pressure vessel storesgas when the gas source flow rate exceeds the gas sink flow rate, andthe primary pressure vessel releases stored gas when the gas source flowrate is less than the gas sink flow rate. The primary pressure vesselmitigates pressure pulsations originating in the gas source flow. Thegas management apparatus also includes a primary variable statematerial. The primary variable state material absorbs the gas when in anabsorptive state, releases the gas in a releasing state, and the primaryvariable state material is characterized by a primary state transitioncondition, such that the primary variable state material is in areleasing state above the primary state transition condition, and anabsorbing state below the primary state transition condition.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the invention briefly described abovewill be rendered by reference to specific embodiments thereof that areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered to be limiting of its scope, the embodiments of theinvention will be described and explained with additional specificityand detail through the use of the accompanying drawings in which:

FIG. 1 shows a schematic representation of the gas generation andmanagement system of the present invention, coupled with a gas consumingsystem.

FIG. 2 shows a side cross-section of an embodiment of a hydrogengenerating PEM electrolyzer of the gas generation system of FIG. 1.

FIG. 3 shows a cross-section along A-A of an embodiment of thecapacitance apparatus of the gas management system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments consistent withthe invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numerals are usedthroughout the drawings and refer to the same or like parts.

As seen in FIG. 1, the gas generation and management system 100 suppliesgas to a system or device, i.e., a gas sink 400 that demands gas foroperation. In an embodiment, the gas sink 400 is a combustion engine,and in particular, a combustion engine that powers a vehicle. The gasgeneration and management system 100 is made of two main subsystems,namely the gas generation system 200, and the gas management system 300.The gas generation system 200 generates gas 202, compresses it intocompressed gas 204, and supplies the compressed gas 204 to the gasmanagement system 300. The gas management system 300 in turn suppliesthe compressed gas 204 to the gas sink 400. Electrolyte solution 206 iscirculated between the gas generation system 200 and the gas managementsystem 300, via an electrolyte solution loop 208 to maintain propertemperatures within the system, as will be discussed further.

From this point forward the gas generator 212 of the gas generating andmanagement system 100 may be referred to as a hydrogen generator 212 attimes. This is not intended to limit the other components of the gasgeneration system 200 to only those related to hydrogen. Further, thisis not intended to limit the gas management system 300 embodimentsdiscussed to only hydrogen gas; the remainder of the gas generationsystem components and the gas management system 300 are intended toencompass any gas. That it is discussed as a hydrogen generator is onlyfor purposes of describing an embodiment.

The gas generation system 200 comprises an electrolyte solutionreservoir 210, a hydrogen generator 212, and a gas compressor 214. Itmay further comprise a vacuum regulator 216 to regulate the vacuumgenerated by the gas compressor, and a dryer 218, to dry the gas oncecompressed. The gas management system 300 comprises a capacitanceapparatus 302, a dryer 304, and a pressure regulator 306. The gasgeneration system 200 further comprises an electrolyte solution 206,which travels in a controlled loop from the hydrogen generator 212 tothe capacitance apparatus 302, to the electrolyte solution reservoir210, and back to the hydrogen generator 212. Connectors in thecomponents, piping between the components and other pumps are known tothose of ordinary skill in the art and therefore will not be discussedfurther here.

The electrolyte solution 206, which comprises water and an electrolytesuch as potassium hydroxide, is fed into the hydrogen generator 212 viaelectrolyte supply line 211. Hydrogen gas 202 is generated in thehydrogen generator 212 in a manner that will be discussed below. Thehydrogen gas is compressed by gas compressor 214. Gas compressor 214 maydraw a strong vacuum on the hydrogen generator 212, and thus a vacuumregulator 216 may be installed between the hydrogen generator 212 andthe gas compressor 214. Gas compressor 214 may take the form of anyavailable compressor. Commercially available units heretofore have beenlimited to reciprocating, piston type compressors. As a consequence,pressure pulsations are created during the compression of the gas, andthose pulsations perpetuate downstream throughout the compressed gas204. Mitigating these pressure pulsations is a function served by thegas management system 300, and is discussed in further detail below.Once compressed, the compressed gas 204 may be dried by a dryer 218.Though not necessary, this step enhances the quality of the compressedgas 204 delivered to the gas management system 300, and ultimately thegas sink 400.

In an embodiment, the gas sink 400 may be a 318 cubic inch, 8 cylinderengine internal combustion engine modified to burn hydrogen gas insteadof gasoline. An embodiment of the gas generation and management system200 described below generates enough hydrogen to sufficiently power thegas sink 400 when the gas sink is the 318 cubic inch 8 cylinder engineinternal combustion engine modified to burn hydrogen gas instead ofgasoline. However, the invention can be used with smaller engines,scaled up to supply enough gas for larger engines, scaled down to supplyenough gas for smaller engines, and embodied to supply different gas toan internal combustion engine that uses a different gas, or a differentkind of engine than an internal combustion engine.

The hydrogen generator 212 can be seen in FIG. 2. It includes a vessel220 comprising a plurality of connected sidewalls 221, a top, a bottom,and two interior gas impermeable walls 222 that divide the vessel 220into two hydrogen generating chambers 224 that surround an oxygengenerating chamber 226. Each hydrogen generating chamber 224 includes ananode 237 and a portal 244 though which hydrogen gas exits to the gascompressor 214. Each oxygen generating chamber 226 includes as manycathodes 240 as there are anodes 237, and portals for electrolyte fluidentry and exit, and electrolyte solution 206, may be comprised of waterand potassium hydroxide, which is supplied from the electrolyte solutionreservoir 210 via an electrolyte solution supply port 250, and completesthe electric circuit. Each interior wall includes a first opening intowhich a proton exchange membrane is positioned, and a second opening,which permits fluid and electrons to travel from one chamber to anadjacent chamber.

The vessel 220 and interior gas impermeable walls 222 are made of TivarH.O.T., manufactured by Quadrant EPP USA, Inc., of Reading, Pa. Bothopenings 228, 230 in the interior gas impermeable walls 222 are disposedbelow an electrolyte solution operating level 232. The proton exchangemembrane 234 may be made from material such as Nafion, manufactured byE.I. du Pont de Nemours and Company of Wilmington, Del. Any fluid thattraverses the first opening 228 must also traverse the proton exchangemembrane 234. The proton exchange membrane 234 may be held in place bysupport plates 236.

Anode 237 is disposed below the operating level of the electrolytesolution 206, and proximate the proton exchange membrane 234. Anode 237comprises a primary anode plate 238 connected to an electric source (notshown) via anode tabs 246, and secondary anode plates 239 connected tothe primary anode plate 238, such that the primary anode plate 238 isthe most centrally disposed plate for even power distribution throughoutthe anode 237 or collection of anodes 237. A nickel alloy material thatserves as a variable state material is also disposed in the hydrogengenerating chamber. The hydrogen generating chamber 224 also includes ahydrogen gas collection area 243 within the hydrogen generating chamber224. Within the hydrogen gas collection area 243 is a hydrogen port 244through which hydrogen can be delivered to the exterior of the vessel.The oxygen generating chamber 226 includes two cathodes 240, disposedbelow the operating level of the electrolyte solution 206, and proximatethe proton exchange membrane 234. Cathodes 240 comprise primary cathodeplates 241 connected to an electric source via cathode tabs 248, andsecondary cathode plates 242 connected to the primary cathode plates241, such that the primary cathode plate 241 of each cathode 240 is themost centrally disposed plate for even power distribution. Electrolytesolution 206 may be supplied to the primary and/or secondary fluidjackets 312, 318, via fluid jacket supply port 252, and may return viathe portal 250.

In an embodiment, the anode 237 itself may be partially or completelymade of the variable state material. In another embodiment, there may beonly a single hydrogen generating chamber 224. The inventors acknowledgea variety of configurations and number of chambers may be employed, butthe underlying inventive concepts remain. As such, those variations areintended to be within the scope of this invention.

In an embodiment the hydrogen generator 212 may be approximately 14″wide, 17″ deep, and 12″ tall, with 0.75″ think gas impermeable walls222, and may hold approximately 0.5 gallons of electrolyte solution 206.The electrolyte solution 206 may contain approximately 3.5% by volume ofelectrolyte, and may be maintained at a level of approximately 6″ in thehydrogen generator 212. The anode plates 238,239, and cathode plates241, 242 may be approximately 4″×12″. The cathode plates may becomprised of 316-L stainless steel. The hydrogen generator 212 may bemaintained during operation at approximately 140° F.

The gas compressor 214 may be capable of delivering a maximum flow rateof, for example, 150 liters per minute of compressed gas 204. However,the hydrogen generator 212 may produce hydrogen gas at varying rates dueto various factors. For example, during operation the temperature withinthe hydrogen generator 212 may fluctuate, the level and chemicalcomposition of the electrolyte solution 206 may also fluctuate, or thevoltage and current delivered through the electrolyte solution 206 mayvary. As a result, the amount of hydrogen gas 202 available to the gascompressor 214 may not match the capacity of the gas compressor 214. Theinventor has found that, on average, the hydrogen generator 212 with thedimensions given above may generate enough hydrogen gas 202 to enablethe gas compressor 214 to deliver an average of approximately 125 litersper minute of compressed gas 204. These figures are not meant to belimiting. These figures simply represent an embodiment. The inventorrecognizes that as pump technology improves, and hydrogen gas generationtechnology evolves, that the numbers may differ from those presented.However, the inventive principles at work do not change, and differentflow rates are intended to be within the scope of this invention.

In operation, the electrolyte solution operating level 232 is maintainedsuch that the anode 237 and cathode 240 remain submerged in theelectrolyte solution 206. It is known in the art that when a current isrun through a circuit of this type, hydrogen gas is generated proximatethe anode 237, and oxygen gas is generated proximate the cathode 240.The hydrogen gas generated by the anode 237 disperses into the hydrogengas collection area 243. From here, the hydrogen gas 202 is pulledthrough hydrogen port 244 via a vacuum generated by gas compressor 214.Particularly advantageous here is that the hydrogen gas generated iskept separate from the oxygen gas, thus preventing loss of hydrogen gasthat occurs if the two are not separated, and portions of the hydrogengas and oxygen gas recombine subsequently.

Proton exchange membranes and their characteristics are known to thosein skilled in the pertinent art. A characteristic of a proton exchangemembrane 234 utilized in the present invention is that such a membraneconducts cations (protons), such as hydrogen protons, but not anions(electrons). It is known that the proton exchange membrane 234 used inan embodiment must be maintained at an operating temperature of overapproximately 100° F., and submerged in the electrolyte solution 206 inorder to function properly. The inventor acknowledges that variationsexist that might require different operating temperatures, but theinventive concepts remain, and the variations are intended to be withinthe scope of this invention. Thus, in this configuration, where anode237 is positioned proximate the proton exchange membrane 234, hydrogenprotons are able to traverse the proton exchange membrane 234 into theoxygen generating chamber 226, but oxygen anions are not able totraverse the proton exchange membrane 234 to enter the hydrogengenerating chamber 224. An advantage of this configuration is that anyhydrogen cations that travel into the oxygen generating chamber 226 maycombine with oxygen anions to form water, thus reducing the oxygenanions, but no oxygen anions can travel through the proton exchangemembrane 234 into the hydrogen generating chamber 224. This ensures thepurity of the hydrogen that is drawn from the hydrogen generatingchamber 224.

As discussed in more detail below, the temperature of the hydrogengenerator 212 may be regulated by removing electrolyte solution 206heated by the hydrogen generation process, and/or adding moreelectrolyte solution 206 from the electrolyte solution reservoir 210,which is cooler. The excess heat may be used for thermal regulation ofother components within the gas generation and management system 100 asnecessary. The sensors, pumps, valves, and piping etc use to accomplishthis thermal regulation are known to those in the art and thus will notbe discussed in any more detail.

The gas management system 300 comprises a capacitance apparatus 302. Thegas management system 300 may also comprise a dryer 304, depicted inFIG. 2, downstream of the capacitance apparatus 302, and a pressureregulator 306 between the capacitance apparatus 302 and the gas sink400. The capacitance apparatus 302 comprises at least a primary pressurevessel 308, a primary variable state material 310, and a means forthermally regulating the primary variable state material 310, which, inan embodiment, is a primary fluid jacket 312 through which a fluid, suchas electrolyte solution 206 from the hydrogen generator 212, may becirculated. The primary variable state material 310 may be disposedwithin the primary pressure vessel 308, it may be in a separatelocation, for example in its own vessel, or it may form part of theprimary pressure vessel structure, or piping etc, or all or anycombination of all of these possibilities. The embodiment describedherein includes the primary pressure vessel 308, a secondary pressurevessel 314, a secondary variable state material 316, and a means forthermally regulating the secondary variable state material 316, which,in an embodiment, is a secondary fluid jacket 318 through which a fluid,such as electrolyte solution 206 from the hydrogen generator 212, may becirculated. The secondary pressure vessel 314 may be disposed betweenthe gas generation system 200 and the primary pressure vessel 308. Thesecondary variable state material 316 may be disposed within thesecondary pressure vessel 314, it may be in a separate location, or itmay form part of the secondary pressure vessel structure, or piping etc,or all or any combination of all of these possibilities. The secondaryvariable state material may be the same material as the primary variablestate material, or may be another material that absorbs the gas beingmanaged. The secondary variable state material may vary in that theequilibrium point may be higher or lower, and/or the interrelation ofpressure and temperature may alter the absorption and/or release rates.

Providing a secondary pressure vessel 314 and secondary variable statematerial 316 adds flexibility to the gas management system 300. Forexample, gas storage capacity can be increased by adding a second, ormore, vessels. Gas storage capacity may be split among two or morevessels, to ease design constraints. However, single vessel systems areenvisioned as embodiments and are intended to be within the scope ofthis disclosure. Such a single vessel system would be the system asdescribed above, without the secondary pressure vessel 314, thesecondary variable state material 316, and the second the secondaryfluid jacket 318.

A variable state material is defined herein to be a material that has atleast three states. In one state the material absorbs a gas. i.e., anabsorptive state. In another state the material releases stored gas.i.e., a releasing state. Another state is simply a neutral state ofequilibrium in between the absorbing state and the releasing state. Thestate of the material is determined generally by an interrelation oftemperature, and pressure of the variable state material and the gas,or, more particularly, the partial pressure of the gas in contact withthe material. Thus, conditions can be created such that the variablestate material will release gas when desired, and absorb gas whendesired. The discussion below is for an embodiment where hydrogen is thegas that is absorbed and released. The fundamental concepts of thisinvention can be used with any gas, so long as there is a variable statematerial that will absorb or release the gas based on the operatingconditions, and the invention is not intended to be limited to variablestate materials that work only with hydrogen.

Variable state materials that absorb hydrogen do so by forming a metalhydride. Conversely, metal hydrides release hydrogen by decomposing themetal hydride. These materials are known to those in the art, and canstore large amounts of hydrogen at low pressures and in relatively smallvolumes. These materials include, but are not limited to materials suchas nickel-metal hydrides. In particular, the inventor has used a rodmade of nickel 200, a commercially pure, wrought nickel. Informationregarding the state of the material at various temperatures andpressures is readily available from the manufacturers. Further, thetemperatures and pressures that create absorbing states and releasingstates of certain variable state materials can be recreated by thecomponents of the gas generation and management system. Thus, the gasgeneration and management system can control the state of the variablestate material as needed. Matching the right material with the designrequirements is relatively straightforward, and is known to those in theart, so it need not be discussed in great detail here. In an embodiment,the variable state material's transition condition, or equilibriumpoint, occurs at about 80° F. However, other temperatures could be useddepending on the system requirements.

As can be seen in FIG. 3, the capacitance apparatus may include a nickel200 rod 316 (i.e., 200 grade pure nickel) disposed in the center of eachthe pressure vessel 308, 314. In an embodiment, the pressure vesselitself may be comprised of a variable state material, such as a Nialloy. The nickel 200 rod may be held in place by a spacer 320. Spacer320 may include holes 322 through which the gas 204 may flow. Thepressure vessel 308, 314 may in turn be held in place with supports 324which secure the pressure vessel 308, 314 inside the outer casing 326.The space between the pressure vessel 308, 314 and the outer casing 326defines the fluid jackets 312, 318. Fluid enters the primary fluidjacket 312 through a primary fluid jacket inlet (not shown) and existsthrough a primary fluid outlet 328. Fluid enters the secondary fluidjacket 318 through a secondary fluid jacket inlet (not shown) and exitsthrough a secondary fluid jacket outlet (not shown).

Thermal regulation of the variable state materials can be accomplishedin any number of ways, and all are intended to be within the scope ofthis invention. In an embodiment, such as the one described herein,thermal regulation of the primary variable state material 310 may beaccomplished via a primary fluid jacket 312 in thermal communicationwith the primary pressure vessel 308 through which a fluid may flow,such that heat may flow from the fluid to the primary variable statematerial 310 inside the primary pressure vessel 308, or vice versa. Inthis manner the state of the primary variable state material 310 can becontrolled. Thermal regulation of the secondary variable state material316 may be accomplished via a secondary fluid jacket 318 in thermalcommunication with the secondary pressure vessel 314 through which afluid may flow, such that heat may flow from the fluid to the secondaryvariable state material 316 inside the secondary pressure vessel 314, orvice versa. In this manner the state of the secondary variable statematerial 318 can be controlled. The fluid that enters the secondaryfluid jacket 318 may be composed partly or entirely of electrolytesolution 206 from the gas generator 212. The fluid that enters theprimary fluid jacket 312 may be composed partly or entirely of the fluidthat leaves the secondary fluid jacket 318. The fluid that exits theprimary fluid jacket 312 may be returned to the electrolyte solutionreservoir 210. Pumps and temperature sensors known to those in the artmay control the flow and composition of the fluids, and will not bediscussed in detail. In the embodiment shown, electrolyte solution 206from the gas generator 212 is the sole fluid circulated to the jacket orjackets. However, the inventor recognizes that other fluids may be mixedin with the electrolyte solution 206 in order to achieve the appropriatetemperatures at the desired locations. Such fluid mixtures and fluidtemperature control is intended to be within the scope of thisinvention.

In an embodiment, the pressure in the primary pressure vessel 308 andthe secondary pressure vessel 314 may be maintained from about 75 psigto about 150 psig. The temperature of the primary variable statematerial 310 in the primary pressure vessel 308 may be maintained atapproximately 80° F., while the temperature of the secondary variablestate material 316 in the secondary pressure vessel 314 may bemaintained at approximately 140° F. Each of the pressure vessels 308,314 may be approximately 2″ in diameter by 8″ long, (i.e., approximately20 cubic inches in volume. The variable state materials 310, 316 may beapproximately 1″ in diameter×6″ long, and be able to absorbapproximately 13,800 standard liters of hydrogen.

In operation, compressed gas 204 generated by the gas generation system200 is delivered to the secondary pressure vessel 314 of the capacitanceapparatus 302, then to the primary pressure vessel 308 of thecapacitance apparatus 302. The secondary pressure vessel 314 and theprimary pressure vessel 308 are directly connected, and other than anyflow losses between them, they maintain essentially the same pressure aseach other. What happens regarding the gas 204 in the pressure vessels308, 314 depends on the compressed gas flow rate into the secondarypressure vessel 314 and the compressed gas flow rate out of the primarypressure vessel 308. The compressed gas flow rate out of the primarypressure vessel 308 is determined by the gas sink 400 demand forcompressed gas 204. For example, but not limiting, when the gas sink 400is a vehicle engine, during high demand periods such as duringacceleration, the demanded compressed gas flow rate will be greater thanwhen cruising at steady speeds. Thus the gas sink 400 demand forcompressed gas 204 may vary greatly during operation. When thecompressed gas flow rate into the secondary pressure vessel 314 isgreater than the compressed gas flow rate out of the primary pressurevessel 308, (i.e., the gas sink 400 demand for compressed gas), thencompressed gas 204 will accumulate within the primary pressure vessel308 and pressure in the primary pressure vessel 308 will increase.Simply put, in that circumstance more compressed gas 204 will be flowinginto the pressure vessels 308, 314 than will be flowing out, andconsequently compressed gas 204 will accumulate in the pressure vessels308, 314. Conversely, when the compressed gas flow rate into thesecondary pressure vessel 314 is less than the compressed gas flow rateout of the primary pressure vessel 308, the compressed gas 204 that hasaccumulated in the pressure vessels 308, 314 will begin to dissipate,i.e., accumulated compressed gas will dissipate from the pressurevessels 308, 314 to be delivered to the gas sink 400.

If the gas generation system 200 were capable of delivering compressedgas 204 such that it could always meet the gas sink demand, then the gasgeneration system 200 could deliver compressed gas 204 directly to thegas sink 400, without an intervening gas management system 300. However,the inventor recognized that in the case where the gas generation system200 were capable of delivering compressed gas 204 such that it couldalways meet the gas sink demand, introducing a gas management system 300may lengthen the life of a gas compressor 214, because the gascompressor 214 may not need to operate as often, and/or it may permitthe use of a less expensive gas compressor 214. Gas compressors 214 inthe current technology are very expensive, and thus this becomes animportant factor.

However, as is the case in the embodiment discussed, where the gasgeneration system 200 can deliver compressed gas 204 such that it meetsmost, but not all of the gas sink 400 demand rates, the gas managementsystem 300 enables the gas generation system 200 to serve as the solesource of hydrogen gas over the entire range of gas sink operation,despite the fact that at times the gas generation system itself mightnot be able to keep up with gas sink demands. In essence, stored gas inthe pressure vessels 308, 314 acts as a second source of compressed gas204 for those times when the gas sink 400 demand rate exceeds the outputcapacity of the gas generation system 200.

In an example embodiment, the gas generation system 200 may delivercompressed gas 204 such that it meets most, but not all of the gas sink400 demand rates, the gas generation system 200 may deliver an averageof 125 liters per minute of compressed gas 204, and the gas sink 400 maydemand anywhere from 80 liters per minute to 150 liters per minute ofcompressed gas 204. It can be seen that so long as the average gasgeneration system 200 delivery rate of 125 liters per minute exceeds theaverage gas sink demand rate, then over time the gas generation system200, when coupled with the gas management system 300, shouldsufficiently supply the gas sink 400. In the inventor's experience, thepressure in the primary pressure vessel 308, and any additional pressurevessels, may often be in the 150 psi range during operation. There maybe times when transient gas sink demands could deplete the supply of gasin the capacitance apparatus 302, (i.e., the stored gas accumulated inthe pressure vessels 308, 314), at which point the gas generation system200 would deliver only as much compressed gas as the gas compressor 214may deliver. However, the inventor recognizes that despite the fact thatengineering trade-offs are inevitable in such a system, properly sizingthe components and matching the gas generation and management system 100to the application will greatly minimize such instances.

The capacitance apparatus 302 serves another function. It mitigatespressure pulsations emanating from the gas compressor 214. As notedearlier, gas compressors of the current technology includereciprocating, piston pumps. These pumps compress and deliver compressedgas sporadically, which results in pressure spikes (i.e., pulsations)being introduced into the compressed gas flow. Were these pressurepulsations not mitigated, the pressure of the compressed gas deliveredto the gas sink 400 would not be steady, but would vary. Consequently,the gas sink 400 would not receive a steady flow of compressed gas 204.The volume of the primary pressure vessel 308, together with theinternal baffling effect, serves to mitigate these pressure pulsations,which improves the quality of the delivered compressed gas 204.

When the gas sink 400 is powered-down, i.e., shut-down, gas generationand management system 100 is also shut-down. The compressed hydrogen inconventional hydrogen powered systems simply sits idle in the gas flowpath between a hydrogen generator and a gas sink, under varying, andsometimes extreme pressures. The gas flow path is defined herein to bethe entire volume where gas is present from where gas originates towhere it is consumed. As a result, there exists a safety hazard not onlyfrom the mechanical pressures present on the pressure vessel, but fromany flammable hydrogen that may leak out. The inventor recognizes thatin industrial settings, with knowledgeable and experienced personnel,leaks may be minimized, but they still do exist. However, a consumer isunlikely to be as knowledgeable and experienced, and the operatingconditions to which the gas generation and management system 100 wouldbe subjected are likely to be less controlled, and thus minimizing thisrisk is of paramount importance. In response to this need, thecapacitance apparatus 302 has been designed to include yet anotherinnovative feature. The primary variable state material 310 is included,as part of the capacitance apparatus 302, either within a primarypressure vessel 308, 314 and/or outside of the pressure vessel 308, 314but within the path of the compressed gas 204. As discussed above, avariable state material 310, 316 can absorb the compressed gas 204, itcan release hydrogen into the compressed gas 204, or in a neutral state,it may do neither. In the capacitance apparatus 302, upon shut-down, thevariable state material 310, 316, which is likely to be in a gasreleasing state during operation, begins to cool, and eventuallytransition to a gas absorbing state. Once in a gas absorbing state, thevariable state material 310, 316 begins to absorb the compressed gas 204in the gas flow path. The system can be configured to permit thevariable state material 310, 316 to absorb most, or all, of thecompressed gas 206 in the gas flow path. The inventor acknowledges thatboth designs would be the result of a balancing of factors, includingthe operating temperatures and pressures in the gas flow path, ambienttemperatures, (and thus the amount of time it takes the variable statematerial 310, 316 to cool), the amount of time the system is powereddown, and the amount and type of variable state material 310, 316. In anembodiment it is preferred that a residual amount of the gas be left inthe gas path. This residual amount would be used to supply the gas sink400 during a subsequent start-up of the gas generation and managementsystem 100. This would be necessary because it may take the gasgeneration system 200 several minutes before it is delivering hydrogengas in quantities sufficient to meet the gas sink 400 demand. Having aresidual amount of gas in the gas flow path would supply the gas sink400 with gas until the gas generation system 200 comes online. Althoughhaving no gas in the gas flow path would be the safest, a residualamount of gas would not pose a significant hazard, but would provide asignificant benefit, i.e., enabling instant system operation.

The variable state material 310, 316 presents one further benefit. Whenunder operating conditions, the primary variable state material 310 maybe releasing gas into the gas flow path, increasing the amount ofcompressed gas 204. This may also improve the quality of the deliveredcompressed gas 204.

Additionally, the state of the variable state material 310, 316 can becontrolled such that its state is independent of the operatingconditions in the gas path. Thus, the variable state material 310, 316can be in a state it would not be when without the thermal regulation.For example, if without the thermal regulation the variable statematerial 310, 316 would be in a gas releasing state, it can bemaintained in a neutral, or gas absorbing state by cooling it.Alternatively, if without the thermal regulation the variable statematerial 310, 316 would be in a gas absorbing state, it can bemaintained in a neutral, or gas releasing state by heating it. Whatstate the variable state material 310, 316 is maintained in is a matterof design choice, and all variations are intended to be within the scopeof this disclosure.

In one embodiment, the temperature of the primary variable statematerial 310 is maintained such that it will enter or be in a gasabsorbing state shortly after shut-down. To accomplish this the primaryvariable state material 310 could be maintained near a neutral state,such that upon a shut down it is closer to a gas absorbing state (i.e.,it is cooler) than it would have been were it not cooled. Alternatively,since it is possible that upon shut-down, when the thermal regulationalso ceases, the primary variable state material 310 may increase intemperature until it meets the temperature of the rest of the gasgeneration and management system 100 as the system cools down, it iscontemplated maintaining the primary variable state material 310 at sucha temperature that even though it does warm for a first portion of asystem shut-down cooling period, it does not warm enough to transition agas absorbing state. (i.e., it remains in a gas absorbing statethroughout the entire shut down period.) This has the advantage ofproviding an almost immediate reduction of gas in the gas path,shortening the time it takes to remove all but the residual amount ofgas in the gas path, and thus more quickly reducing the risks associatedwith compressed, flammable gas. The inventor acknowledges that choosingthe proper material to serve as the primary variable state material is amatter of matching known characteristics of variable state materialswith the system requirements. The underlying concepts remain, andvariations in materials are intended to be within the scope of thisinvention.

In an embodiment, the secondary variable state material 316 may be keptin a gas releasing state, while the primary variable state material 310may be kept at or near a gas absorbing state, as discussed above. In anembodiment, the equilibrium point of the secondary variable statematerial is the same or similar to that of the primary variable statematerial, but the secondary variable state material is maintained in adifferent state than the primary variable state material duringoperation, such that it is in a releasing state during operation. Inthis manner two purposes are simultaneously served by the variable statematerials. The secondary variable state material 316 releases hydrogengas into the compressed gas 204 flow during operation. Upon shut-down,the primary variable state material 310 more quickly enters, or remainsin, the hydrogen absorption state, thereby more quickly rendering thegas generation and management system 100 less susceptible to the dangersassociated with compressed, flammable gas. Subsequent to shut-down, whenthe secondary variable state material 316 cools sufficiently, it toowill then enter a gas absorbing state, and assist in removing hydrogenfrom the gas path.

In an embodiment, the hydrogen generator 212 is regulated to an averagetemperature of approximately 140° F. Warmed electrolyte solution 206from the hydrogen generator 212 is circulated into the secondary fluidjacket 318 where it warms the secondary variable state material 316.Sufficient heat is transferred to the secondary variable state material316 such that when electrolyte solution 206 exits the secondary fluidjacket 318 and enters the primary fluid jacket 312, it is at atemperature that will maintain the primary variable state material in aneutral or hydrogen absorbing state, or sufficiently close to a hydrogenabsorbing state that it will enter a hydrogen absorbing state uponshut-down sooner than will the secondary variable state material 316.

It can be seen that the inventor has innovatively created a gasgeneration and management system that provides a steady flow ofcompressed gas to a gas sink that may, at times, demand a greater flowrate than the individual components of the gas generation and managementsystem could deliver. The gas generation and management system alsoprovides compressed gas during start-up operations, yet renders the gasgeneration and management system much safer than conventional compressedgas systems by minimizing the amount of compressed gas present in thegas generation and management when the system is not operational. Allthis is done while minimizing the cost of components, in a simple, yeteffective manner.

While the preferred embodiments of the present invention have been shownand described herein, it will be obvious that such embodiments areprovided by way of example only and not of limitation. Numerousvariations, changes and substitutions will occur to those skilled in theart without departing from the teaching of the present invention.Accordingly, it is intended that the invention be interpreted within thefull spirit and scope of the appended claims.

1. A hydrogen gas generator, for use with an electric source,comprising: a fluid reservoir; a vessel holding an electrolyte solution;a gas impermeable wall dividing the vessel into a hydrogen generatingchamber and an oxygen generating chamber, the gas impermeable wallcomprising a first opening and a second opening both disposed below anoperating level of the electrolyte solution, wherein the second openingpermits the electrolyte solution to traverse the gas impermeable wall; aPEM installed in the first opening such that any fluid communicationthrough the first opening must pass through the PEM; an anode in thehydrogen generating chamber, disposed below the operating level of theelectrolyte solution and proximate the PEM; a nickel alloy materialdisposed in the hydrogen generating chamber, wherein the nickel alloymaterial absorbs hydrogen when below approximately 80° F., and releaseshydrogen when above approximately 80° F.; a cathode in the oxygengenerating chamber, disposed below the operating level of theelectrolyte solution; and a hydrogen gas collection area within thehydrogen generating chambers comprising a port through which hydrogencan be delivered to the exterior of the vessel, wherein the anode andcathode are connected to the electric source, and the electric source,anode, cathode, and electrolyte solution form an electric circuit. 2.The hydrogen gas generator of claim 1, wherein the anode is comprised ofthe variable state material.
 3. The hydrogen gas generator of claim 1,further comprising: a second gas impermeable wall comprising a secondPEM disposed in the second gas impermeable wall, such that the first andsecond gas impermeable walls create three chambers, wherein the thirdchamber is an additional hydrogen generating chamber comprising an anodeand a nickel alloy material, and wherein the oxygen generating chamberis disposed between the hydrogen generating chambers.
 4. The hydrogengas generator of claim 3, wherein the anodes are comprised of the nickelalloy material.
 5. A method for generating hydrogen gas in a vesselcomprising at least one oxygen generating chamber comprising a cathode,and at least one hydrogen generating chamber comprising an anode,wherein the chambers are separated by a gas impermeable wall comprisinga first opening and a second opening, wherein electrolyte solution isfree to pass through the second opening, and wherein any fluidcommunication through the first opening must pass through a PEM, themethod comprising: maintaining a temperature within the vessel of over85° F. during operation; absorbing hydrogen present in the hydrogengenerating chamber when the temperature within the vessel falls belowapproximately 85° F. using a variable state material placed in thehydrogen chamber, wherein the variable state material absorbs hydrogenwhen the variable state material temperature falls below approximately80° F.; supplying electrolyte solution from a reservoir to the vessel;maintaining the electrolyte solution level such that the anode, cathode,and PEM remain submerged during operation, and the PEM remains submergedeven when the system is not operating; supplying electricity from anexternal source such that the electrolyte solution forms part of theelectric path in the vessel; delivering any hydrogen that is generatedin the hydrogen generating chamber; and permitting any hydrogen thatpasses through the PEM into the oxygen generating chamber to combinewith any oxygen present in the oxygen chamber.
 6. The method forgenerating hydrogen gas of claim 5, wherein the anode is comprised ofthe variable state material.
 7. The method for generating hydrogen gasof claim 5, wherein the vessel comprises two gas impermeable walls eachcomprising a first opening and a second opening, wherein the walls formtwo hydrogen generating chambers each comprising an anode surrounding asingle oxygen generating chamber comprising a cathode.
 8. The method forgenerating hydrogen gas of claim 7, wherein the anodes are comprised ofthe variable state material.